Veneer breakers



Aug. 30, 1966 H. VONHOF ETAL VENEER BREAKERS 2 SheetsSheet 1 Filed May 12, 1965 HERBERT VONHOF IVAN GVMYERS I NV E NTO RS ATTORNEYS Aug. 30, 1966 Filed May 12 1965 H. VONHOF ETAL VENEER BREAKERS 2 Sheets-Sheet 2 H /34 1 IXW FIG 4 HERBERT VONHOF IVAN G. MYERS I NVENTORS ATTORNEYS United States Patent VENEER BREAKERS Herbert Vonhof and Ivan G. Myers, Shelton, Wash, assignors to Simpson Timber Company, Seattle, Wash, a corporation of Washington Filed May 12, 1965, Ser. No. 455,084 9 Claims. (Cl. 225-97) The present invention relates to veneer breakers for piercing and separating a moving web of wood veneer. More specifically, the invention relates to a below-belt mechanical veneer breaker having an improved actuating linkage and control system for the breaker arms.

Veneer breakers are devices of a rather recent origin and are used in high speed automated systems wherein veneer is produced on a peeler lathe and is fed into a multi-deck conveyor or tray system for temporary storage and for transfer to veneer clippers. Since the veneer comes from the peeler in a continuous web or ribbon, it must be broken when a storage tray is filled so that the web may be fed into another tray and so on. Until ten or twelve years ago this breaking was done by hand since conveyor speeds were relatively slow and conveyors were manually controlled. With the advent of automation and automatic speed synchronizing between the peeler and conveyors or tipples, speeds are rather high and the veneer may be moved at a rate as high as 800 feet per minute. Since the breaking can no longer be done by hand at these speeds and known veneer clippers are only suitable for cutting moving veneer at a relatively slow speed in the order of 130 to 200 feet per minute or slower, the veneer breaker came into being.

Since clipping is impossible at the high speed mentioned, mechanical veneer breakers are used in most instances which provide a plurality of individual arms which move into the path of the moving veneer ribbon and pierce the ribbon to physically separate it with a rather ragged break as opposed to a cutting or clipping action. The present invention deals with such a mechanical breaker known as a below-belt veneer breaker wherein shaft mounted arms located below the veneer ribbon rotate upwardly against the direction of veneer travel and then return. As can be appreciated, the problem in operating such a set of breaker arms involves the provision of an extremely rapid stroke of the arms in an upward direction and then downwardly in one cycle. Thus initial acceleration to the mass of the arms must be provided and effective deceleration of the rapidly moving arms must be accomplished since the force of the returning arms could reach destructive proportions. In the past, veneer breakers were provided with an actuating piston rod which raised the breaker arms and then a control valve was reversed in order to retract the piston rod to return the breaker arms to the starting position. This type of actuation has proven to be unsatisfactory as being too slow and requiring complicated valving and controls.

Accordingly, the primary object of the present invention is to provide a veneer breaker with an improved actuating system involving a toggle linkage for raising and lowering the breaker arms in one stroke of the piston rod of an actuating cylinder to yield a much faster action, eliminate piston reversal in mid cycle and simplify valving controls.

A further object of the present invention is to provide a veneer breaker actuating system of the character described with an air pressure control system which provides a high initial pressure to accelerate the breaker arms upwardly, a low air pressure to accelerate the arms downwardly and a final air pressure which is only a fraction of the initial air pressure to reduce shock loads on the device, to thus accommodate the change in mechanical advantage which occurs during the unidirectional travel of the piston rod.

Other more particular objects and advantages of the invention will, with the foregoing, appear and be understood in the course of the following description and claims.

Reference is now made to the accompanying drawings in which:

FIG. 1 is a schematic illustration of a veneer breaker device as utilized in conjunction with a peeler and a multi-deck conveyor system;

FIG. 2 is a cross sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a detailed perspective view of the breaker arm actuating linkage; and

FIG. 4 is a schematic view of the air pressure system for actuating the breaker arm linkage.

Referring now to the drawings wherein like reference numerals indicate identical parts in the various views, FIG. 1 illustrates the position of the veneer breaker unit 1 with respect to the overall veneer handling system. As shown in FIG. 1, the web or ribbon of veneer 2 is peeled from a peeler log 3 which is mounted in a lathe which rotates the log against the knife 4. The continuous web 2 feeds onto a conveyor system which delivers the web to a number of vertically spaced veneer storage trays 6 as illustrated. The conveyor system in the present illustration comprises a trash gate 7 which is movable between the full line and dotted line positions shown in FIG. 1 and which may be selectively controlled by an operator for directing veneer scraps to the trash conveyor 8 in a manner well known to the art. Although the details of various conveyor systems may differ, the web 2 is usually fed onto a tipple swingable conveyor belt or belts which may be selectively controlled to direct the web to a chosen one of the trays 6. As each tray is filled the web of veneer is broken and directed to the next chosen tray and so on. In the present instance, a triple tipple arrangement is shown wherein the primary tipple or swingable conveyor 9 'has two alternate positions shown by the full and dotted line positions in FIG. 1 for feeding the web to either one of the two secondary tipples 11 and 12. It will be understood of course that an operator controls the movement of the primary and secondary tipples so that the web may be directed to any one of the trays 6.

The breaker unit indicated at 1 in FIG. 1 is carried on the frame structure of the primary tipple 9 shown in detail in FIGS. 2 and 3. Referring to FIGS. 2 and 3, the veneer breaker comprises a plurality of breaker arms 13 which are keyed to the rotatable shaft 14, mounted for rotation beneath the belts 6 of the primary tipple. The shaft 14 may be journaled in suitable bearings 17 carried by the tipple frame as shown in FIG. 2. The breaker arms 13 are movable between the full and dotted line positions as shown in FIG. 1 for piercing the moving web of veneer to break it.

The linkage for operating the shaft 14 comprises the toggle arrangement shown in detail in FIG. 3 which includes a first pair of toggle links 18 which are pivoted on the pin 19 carried by the bearing block 21. The block 21 is fixed to the cylinder mounting brackets 22 which are carried by the frame of the tipple. The links 18 are pivoted at their upper ends on the pin 23 carried by the bifurcated member 24 on the end of the piston :rod 26. A second toggle link 27 is also pivoted on the pin 23 at one end and pivotally connected to the crank arm 28 by means of the pin 29. The crank arm 28 is keyed to the shaft 14 so as to rotate the shaft 14 in a manner to be described.

The cylinder 30 comprises a double-acting fluid cylinder which is supported by the brackets 22 as illustrated in FIG. 3. The cylinder 30 is rotatably mounted between the brackets 22 on suitable pivot pins 31 which provide an axis around which the cylinder rotates to accommodate the movement of the links 18. In the present instance, the cylinder 30 is an air cylinder and the piston rod is cushioned at the end of its travel in each direction in a manner well known to the prior art.

With the described linkage, it will be seen that the forward stroke of the piston rod 26 from the position shown in the drawings will initially rotate [the shaft 14 clockwise to raise the breaker arms 13 to the dotted line position shown in FIG. 1 for piercing the moving web. As the rod 26 reaches a position where the pivot pins 19, 23 and 29 are aligned, the arms 13 have reached their limit of travel and further forward movement of the piston rod then reverses the direction of rotation of the shaft 14 causing the arms to return to the lowered position when the piston rod is fully extended. When the cylinder 30 is reversed, the return stroke of the piston rod 26 repeats the raising and lowering cycle of the breaker arms. Thus, one full stroke of the piston rod 26 in either direction serves to both raise and lower the breaker arms giving much faster action, eliminating piston reversal in mid cycle and simplifying the valving control for the cylinder.

As will be apparent to those skilled in the art, the power requirements for operating the toggle linkage to raise and lower the breaker arms through one cycle is not uniform since the mechanical advantage changes during the travel of the piston rod. Since this is true, a constant air pressure applied to the air cylinder 30 is not only inefficient but may interfere with the operation of the device. It will be understood that a relatively high pressure is required initially to accelerate the breaker arms 13 rapidly upward at the beginning of the stroke of the piston rod 26. At the beginning of the stroke, a small amount of piston travel causes a relatively great amount of breaker arm travel. As the toggle links 18 and 27 approach dead center the mechanical advantage changes such that a large amount of piston travel is required to move the breaker arms a small amount. As the toggle linkage reaches dead center a lower air pressure will sufiice to accelerate the arms downwardly. Finally, as the arms approach the return position, the mechanical advantage again changes since the mass of the rapidly moving arms exerts a high force in the direction of piston travel at the end of the stroke. Although the air cylinder used may be cushioned at both ends of its stroke, the decelerating force could reach destructive proportions if the initially required high air pressure were kept constant as in conventional air cylinder application. According to the present invention, a novel air pressure control system is provided which will apply a relatively high initial pressure for accelerating the breaker arms rapidly upwardly. After the piston has traveled approximately half its stroke such that the toggle linkage is on dead center, the air pressure has dropped and may be in the neighborhood of one half its initial value, which is sufiicient to accelerate the breaker arms downward for the return stroke. Deceleration and stopping in the return position are accomplished by the air cylinder cushions aided by the fact that, as the piston rod reaches the end of its travel the air pressure control system has caused a drop in pressure so that the working pressure in the cylinder is only a fraction of the original value.

The air pressure control system for accomplishing the pressure reduction feature is shown schematically in FIG. 4. As illustrated, the cylinder 30 comprises a double-acting fluid cylinder with air pressure conduits 32 and 33 communicating with opposite ends of the cylinder. A conventional four-way solenoid valve 34 serves to selectively admit air under pressure from the pressure line 36 and to simultaneously exhaust air pressure to the exhaust conduit 37 in a well known manner. The pressure side of the system may be connceted to a suitable source of air pressure with the pressure being regulated by the pressure regulator 38. An air reservoir or tank 39 of a fixed capacity is located in the supply line 36 with a restrictor or fixed orifice 41 being located between the pressure regulator 38 and the tank 39. In the present embodiment, the volume of the tank 39 equals approximately one-half of the displacement of the air cylinder 30. A variable flow regulator 42 may be located on the exhaust side of the valve 34 for a purpose to be described.

The operation of the device will now be described in detail assuming that the regular 38 has been set to obtain a gauge pressure of 60 p.s.i. in the tank 39, the volume of which is one-half the displacement of the air cylinder 30 as previously mentioned. It will be understood, of course, that the specific pressure values herein mentioned and the size of the tank 39 relative to the cylinder 30 may be varied in any given instance to con trol the magnitude of pressure reduction to meet particular power requirements. In the present example, the volume of the air lines and the effect of air temperature change due to expansion of air will be ignored and atmospheric pressure will be assumed to be 15 p.s.i. for simplicity.

The breaker arms are actuated by shifting the valve 34 to admit air pressure to the right end of the cylinder 30 and to exhaust the air from the left end in a conventional manner. Because of the fixed orifice 41, the reservoir or tank 39 acts instantaneously as a closed tank containing a fixed quantity of air. Full tank pressure which, in this instance is 60 p.s.i. gauge pressure or 75 p.s.i. absolute pressure, initiates the action of the breaker arms for rapid upward acceleration. Since the left end of the cylinder is exhausted against atmospheric pressure, however, the net efi'ect on the pistons to move the rod 26 will be 60 p.s.i. When the piston rod has traveled one-half its stroke, the combined volume of the tank and the cylinder is twice the original volume of the tank and hence, using the formula P V =P V the absolute pressure in the cylinder is 37 /2 p.s.i. or 22 p.s.i. net pressure on the piston which is sufficient to move the breaker arms downwardly. After the piston rod has traveled its full stroke, the combined volume of the tank and the cylinder is three times the original volume of the tank and, using the formula P V =P V the absolute pressure in the cylinder is 25 p.s.i. or 10 p.s.i. net pressure acting to move the arms, thus relieving the deceleration problem. Since the breaker operation is intermittent, adequate time is available between strokes for the reservoir 39 to be refilled through the restriction 41. Were it not for the pressure reduction feature of the control system, the downward speed of the arms would be much greater and their increased kinetic energy plus the full pressure on the piston would greatly increase deceleration forces, causing excessive shock loads, possible parts failure or at-least reduced life of the mechanism and difficulty in attaining smooth action. The air flow regulator 42 which constitutes a variable restriction in the exhaust line also provides for the further control of speed and smoothness of operation.

It will be apparent to those skilled in the art that the present invention provides significant improvements in veneer breaker actuation in the nature of simplification of structure and rapid and efiicient operation with the elimination of shock loads and unnecessary hammering. The arrangement and types of structural components utilized may be subjected to numerous modifications well within the purview of this invention and applicants intend only to be limited to a liberal interpretation of the specification and appended claims. Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In combination with a veneer breaker having a plurality of breaker arms fixed to a rotatable shaft for movement into the path of a moving veneer ribbon, acmating means comprising; a crank arm on said shaft, a

double acting fluid cylinder having an extensible piston rod, means to actuate said cylinder, and over-center toggle linkage means for connecting said rod to said crank arm, whereby a single stroke of said rod causes rotation of said shaft alternately in both directions to operate and return said breaker arms.

2. The combination according to claim 1 wherein said means to actuate said double acting cylinder comprises; a source of air pressure, valve and conduit means for selectively connecting said source of air pressure to either end of said cylinder and to exhaust the opposite end thereof, and means in said conduit to control the air pressure for delivering a high initial air pressure and providing for reduction of the pressure applied to said cylinder as the piston rod continues its stroke.

3. The combination according to claim 2 wherein said means to control the air pressure comprises an air tank of fixed volume in said conduit means and restrictor means between said air pressure source and said tank to control the flow of air to said tank.

4. In combination with a veneer breaker having a plurality of breaker arms fixed to a rotatable shaft for movement into the path of a moving veneer ribbon, actuating means comprising; a crank arm on said shaft, a double acting fluid cylinder having an extensible piston rod, means to actuate said cylinder, toggle linkage means for connecting said rod to operate said crank arm, said toggle linkage means including first link means pivotally connected to a fixed pivotal axis and to the end of the rod, and second link means pivotally connected to said rod and to said crank arm, whereby movement of said piston rod in one direction causes rotation of said shaft alternately in both directions to operate and return said breaker arms.

5. The combination according to claim 4 wherein said means to actuate said double acting cylinder comprises; a source of air pressure, valve and conduit means for selectively connecting said source of air pressure to either end of said cylinder and to exhaust the opposite end thereof, and means in said conduit to control the air pressure for delivering a high initial air pressure and providing for reduction of the pressure applied to said cylinder as the piston rod continues its stroke.

6. The combination according to claim 5 wherein said means to control the air pressure comprises an air tank of fixed volume in said conduit means and restrictor means between said air pressure source and said tank to control the flow of air to said tank.

7. In combination the conveyor means for moving a continuous ribbon of wood veneer, a veneer breaker device comprising; a shaft journaled for rotation beneath said conveyor means, a plurality of breaker arms fixed to said shaft for movement into the path of a moving veneer ribbon, a crank arm on said shaft, a double acting fluid cylinder having an extensible piston rod, means to actuate said cylinder, toggle linkage means for connecting said rod to operate said crank arm, said toggle linka-ge means including first link means pivotally connected to a fixed pivotal axis and to the end of the rod, second link means pivotally connected to said rod and to said crank arm, and means for mounting said cylinder to accommodate swinging movement of said first link means, whereby movement of said piston rod in one direction causes rotation of said shaft alternately in both directions to operate and return said breaker arms.

8. The combination according to claim 7 wherein said means to actuate said double acting cylinder comprises; a source of air pressure, valve and conduit means for selectively connecting said source of air pressure to either end of said cylinder and to exhaust the opposite end thereof, and means in said conduit to control the air pressure for delivering a high initial air pressure and providing for reduction of the pressure applied to said cylinder as the piston rod continues its stroke.

9. The combination of claim 8 wherein said means to control the air pressure comprises an air tank of fixed volume in said conduit means and restrictor means between said air pressure source and said tank to control the flow of air to said tank.

No references cited.

WILLIAM W. DYER, 111., Primary Examiner.

J. M. MEISTER, Assistant Examiner. 

1. IN COMBINATION WITH A VENEER BREAKER HAVING A PLURALITY OF BREAKER ARMS FIXED TO A ROTATABLE SHAFT FOR MOVEMENT INTO THE PATH OF A MOVING VENEER RIBBON, ACTUATING MEANS COMPRISING: A CRANK ARM ON SAID SHAFT, A DOUBLE ACTING FLUID CYLINDER HAVING AN EXTENSIBLE PISTON ROD, MEANS TO ACTUATE SAID CYLINDER, AND OVER-CENTER TOGGLE LINKAGE MEANS FOR CONNECTING SAID ROD TO SAID CRANK ARM WHEREBY A SINGLE STROKE OF SAID ROD CAUSES ROTATION OF SAID SHAFT ALTERNATELY IN BOTH DIRECTIONS TO OPERATE AND RETURN SAID BREAKER ARMS. 